[UPDATE: iOS 4.3.1 solves the battery problem. Read more here.]
I’ve been sick with bronchitis for more than a week following six germ-filled plane trips around the country. One good thing has come of my illness: I didn’t sync my iPhone to my iMac for the past week, and thus don’t have the iOS 4.3 update that is, by many reports, taking a toll on the iPhone’s battery life.
For details, see reports from Cult of Mac, GeekBeat.TV (“turn off Ping,” was their suggestion), and 9to5mac. Some users report that the battery problem was solved by resetting Notifications and Mail Push and rebooting the phone.
There is absolutely no reason why you need to upgrade to iOS 4.3 immediately, so I strongly suggest declining the upgrade when iTunes offers it to you. My guess is that there will be an update in a few weeks that will resolve the underlying problem or that someone will come up with a step-by-step solution for restoring performance. I’ll certainly be on the lookout for the latter.